List of United States Senators from Illinois

Illinois was admitted to the Union on December 3, 1818, and has been represented in the United States Senate by 47 senators. Senators from Illinois are elected to Class 2 and Class 3.

The Senate twice refused to seat Frank L. Smith, in December 1926 for an appointed term and in March 1927 for an elected one, due to corruption, but he is included in this list because Smith and the Governor considered him to be a senator for approximately two years.

Three of the seven African Americans to hold U.S. Senate seats since Reconstruction have held Illinois's Class 3 seat.

^ abDeneen defeated McCormick for the Republican nomination in 1924 and won the subsequent general election. McCormick died shortly before the end of his term, so Deneen was appointed to replace him.

^Shields was not seated because he had not been a citizen for the required nine years. He reached that mark on October 21, 1949, so his subsequent election was accepted by the Senate.

^ abSmith defeated McKinely for the Republican nomination in 1926 and won the subsequent general election. McKinley died shortly before the end of his term, so Smith was appointed to replace him.

^When Smith presented his credentials to serve the remainder of McKinely's term, the Senate refused to seat him based on what it saw as an election rife with fraud and corruption. When Smith returned with his credentials for the term he was elected to, the Senate again refused to seat him for the same reasons. Smith and the Governor considered him to be the rightful senator, but he resigned in February 1928. The Senate does not consider him to have been a senator.

^Kirk was elected to fill the remainder of Barack Obama's term in a special election held the same day as the general election for the next term, which he also won.